In the beverage producing industry, a variety of apparatuses and methods for treating containers is known. Examples of such apparatuses are moulding units or blow-moulding units, which convert plastic preforms into plastic containers. Further examples are heating devices, which heat the containers or which close a mould carrier for such preforms. Apart from that, cleaning devices for such containers are also known.
In the case of many of these machines it is necessary that the containers to be treated are conveyed not only along a specified transport path, but that a treatment unit of the machine or the containers themselves are moved in a direction extending vertically relative to this path of travel, in order to carry out a certain treatment process. Usually, a special treatment unit such as a blow nozzle or a stretching rod is moved for this purpose, but it would also be possible to move a means of transport holding the container in an appropriate manner. In order to carry out such movements, guiding cams are frequently employed in the prior art, which guiding cams interact for example with guiding rollers of the corresponding treatment unit, in order to effect this movement vertically relative to the transport path.
These guiding cams work reliably and in a satisfactory manner even over longer periods of time. For example, DE 2354391 describes a multiple station rotary table blow moulding machine. In this disclosure, attention is drawn to the fact that a certain play in the form of a tolerance between the external diameter of the follower and a cam path needs to be provided. However, it is also pointed out that this play shouldn't be made to be excessively large, since otherwise there is a risk of the corresponding guiding path wearing out. U.S. Pat. No. 5,531,588 describes an adjustable cam guide for a blow moulding machine.
From DE 10 2007 011 060 A1, a method for blow moulding containers is known, wherein a support element having a movable cam segment may be coupled in such a manner that the support element is arranged to be controllable either in an operating position or in an idle position. However, this document, too, does not include any reference to reducing the wear of such cam segments. Also, this possibility of coupling does not result in a corresponding wear reduction.
Further, there has been a tendency in some cases recently to replace mechanical guiding cams with separate servo-motor drives of the treatment units. Nevertheless, the use of guiding cams has proven to be very reliable in many areas.
It may therefore be desirable to provide methods and apparatuses for achieving a reduction of wear on mechanical guiding cams when used in apparatuses for treating containers.